JP2006201226A - Optical coupler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To have a wide usable range of environmental temperatures and to obtain stable optical characteristics. <P>SOLUTION: A lens member 55 is stuck to a lead frame 36 through a transparent adhesive resin 41 and is not transfer-molded by a sealant 37. As a result, the transparent adhesive resin 41 can be used as a buffer member for a thermal stress due to a difference in the linear expansion coefficient between the lead frame 36 and the lens member 55. Use of a low Young's modulus resin such as a silicone based resin can greatly reduce the thermal stress affecting the lens member 55 and thereby prevent the lens member 55 from being damaged or deformed. Further, the linear expansion coefficient can be reduced by adding a filler to the sealant 37, which enables the optical coupler to be used under an environment of wider temperature range such as -40 to 115°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical coupler having an optical element, and more particularly to an optical coupler that can be used for home communication, in-car communication, LAN (Local Area Network), etc. using an optical fiber as a transmission medium.

  Conventionally, optical couplers that optically couple optical elements such as light emitting diodes (LEDs) and photodiodes (PDs) with optical fibers have been known. It is used for optical communication in automobiles. In general, optical couplers are known in which an optical element is sealed with a transparent mold resin (transfer molding) and in an airtight seal (hermetic seal) in a metallic case.

  FIG. 9 shows a longitudinal section of the optical coupler 1 as the first prior art. In this optical coupler 1, an optical element 3 is mounted on a lead frame 2, and the optical element 3 is transfer molded with a transparent mold resin 4. A lens portion 6 is formed at a position facing the optical surface (surface on which light enters and exits) 5 of the optical element 3 in the transparent mold resin 4. The optical element 3 and the lead frame 2 are electrically connected by a bonding wire 8.

  In the optical coupler 1 having the above configuration, when the optical element 3 is a light emitting element, the light emitted from the optical surface 5 passes through the transparent mold resin 4 and is condensed by the lens unit 6. The light is emitted toward the end face 7 a of the optical fiber 7. The light emitted from the lens unit 6 is incident on the optical fiber 7.

  When the optical element 3 is a light receiving element, the light emitted from the end surface 7a of the optical fiber 7 is condensed by the lens portion 6 of the transparent mold resin 4 and transmitted through the transparent mold resin 4. Incident on the optical surface 5. In this way, the optical fiber 7 and the optical element 3 are so-called optically coupled so that light can be transmitted.

  FIG. 10 shows a longitudinal section of an optical coupler 11 as a second prior art (Patent Document 1 (Japanese Patent Laid-Open No. 60-12782 (FIG. 3))). In this optical coupler 11, an optical element 12 is disposed at a position of a through hole 15 in a surface 13 a opposite to the optical fiber 14 side of the lead frame 13 (hereinafter referred to as a back surface), and is transfer molded by a transparent mold resin 16. ing.

  In the optical coupler 11 having the above-described configuration, the light that enters and exits the optical surface 17 of the optical element 12 passes through the through hole 15 and transmits through the transparent mold resin 16, so that the end surface 14 a of the optical fiber 14. Incoming and outgoing.

  In such an optical coupler 11, the bonding wire 18 that electrically connects the optical element 12 and the lead frame 13 can be disposed on the back surface 13 a side of the lead frame 13. Therefore, compared with the case of the optical coupler 1, the distance between the optical element 12 and the optical fiber 14 can be narrowed (that is, the thickness of the transparent mold resin 16 on the optical fiber 14 side) can be reduced. Thus, when a light emitting element having a large radiation angle is used as the optical element 12, there is an effect that the light use efficiency can be improved.

  FIG. 11 shows a longitudinal sectional view of an optical coupler 21 as a third prior art (Patent Document 2 (Japanese Patent Laid-Open No. 59-180515 (FIG. 2))). The optical coupler 21 is hermetically sealed by a lens cap 25 in which an optical element 22 is disposed at the bottom of a recess 23 a of a metal stem 23 and a lens 24 is provided. The optical element 22 and the lead terminal 26 are electrically connected by a bonding wire 27.

  In the optical coupler 21 configured as described above, the light that enters and exits the optical element 22 is collected by the lens 24 of the lens cap 25 and enters and exits the end face 28 a of the optical fiber 28.

  However, each of the conventional optical couplers has the following problems. That is, in the first and second conventional techniques, the optical elements 3 and 12 are arranged on the lead frames 2 and 13 and sealed with the transparent mold resins 4 and 16. In this case, since the linear expansion coefficient difference between the transparent mold resins 4 and 16 and the lead frames 2 and 13 is large, there is a problem that the environmental temperature at which the optical couplers 1 and 11 can be used is limited. is there.

  That is, in the first prior art, generally, the linear expansion coefficient of the epoxy resin used as the transparent mold resin 4 is 60 ppm / K to 70 ppm / K. In contrast, the linear expansion coefficient of copper or the like used for the lead frame 2 is about 20 ppm / K, and the difference between the linear expansion coefficients is large. Therefore, when the environmental temperature changes, the transparent mold resin 4 and the lead frame 2 A large thermal stress is generated at the interface. Therefore, there are problems that the transparent mold resin 4 is broken (cracked), the transparent mold resin 4 is peeled off from the lead frame 2, and the lens portion 6 is deformed to change the optical characteristics.

  In the second prior art, the transparent mold resin 16 that has entered the through hole 15 of the lead frame 13 is peeled off from the surface of the optical element 12 due to thermal stress, and the characteristics of the optical element 12 change (for example, In the case where the optical element 12 is an LED, there is a problem that the refractive index of the surface of the optical surface 17 in contact with the optical element 12 changes due to the peeling of the transparent mold resin 16 and the light extraction efficiency changes. On the other hand, it is known that the linear expansion coefficient can be reduced by adding a filler to the mold resin. In this case, however, the transparent mold resin 16 becomes cloudy and optical characteristics deteriorate (transmittance decreases). Therefore, it is difficult to use for the optical coupler 11. From the above, the operating environment temperature of the optical coupler 11 is limited to about −20 ° C. to 80 ° C.

In the third prior art, the hermetic seal is used as described above. In that case, although the influence of the thermal stress as described in the second prior art is small, the use of the metal stem 23 increases the price of the optical coupler 21 and makes it difficult to reduce the size. There is. Further, since an air layer is formed between the optical element 22 and the lens cap 25, there is a problem that reflection loss of light is large.
Japanese Patent Laid-Open No. 60-12782 (FIG. 3) JP 59-180515 A (FIG. 2)

  Accordingly, an object of the present invention is to provide a small and low-cost optical coupler that can be used in a wide range of ambient temperature, can obtain stable optical characteristics.

In order to solve the above problems, an optical coupler of the present invention is
An optical element;
A lead frame mounted with the optical element and electrically connected to the optical element;
A lens member including a lens that collects light incident on or emitted from the optical element;
The lens member is disposed so that the lens faces an optical surface that is a surface on which light in the optical element is incident or emitted,
A transparent resin is interposed between the lens member and the optical surface of the optical element.

  According to the above configuration, a small lens can be used as compared with a lens formed by a transfer mold that also serves to seal an element like the optical coupler 1 in the first prior art. The thermal stress applied to the member can be reduced. Accordingly, deformation or breakage of the lens member and peeling from the lead frame can be made difficult to occur. Furthermore, the transparent resin can be used as a buffer member for thermal stress generated between the lead frame and the lens member due to a difference in linear expansion coefficient between the lead frame and the lens member. Therefore, it becomes possible to use in a wide temperature range. Furthermore, since the transparent resin is interposed between the lens member and the optical surface of the optical element, the optical surface of the optical element can be protected.

In the optical coupler of one embodiment,
The transparent resin is also spread on the surface of the lead frame where the lens member is disposed,
The lens member is bonded to the lead frame via the transparent resin spreading on the surface of the lead frame, and is not in direct contact with the lead frame.

  According to this embodiment, since the lens member is not in direct contact with the lead frame, the thermal stress buffering effect by the transparent resin is enhanced, and the thermal stress applied to the lens member can be reliably reduced. it can.

In the optical coupler of one embodiment,
The transparent resin has a Young's modulus of 1 GPa or less.

  According to this embodiment, by using a resin having a Young's modulus of 1 GPa or less as the transparent resin, the transparent resin serves as a buffer member with better thermal stress acting between the lens member and the lead frame. Can function. Therefore, use in a wider temperature range is possible.

In the optical coupler of one embodiment,
The transparent resin is a silicon compound.

  According to this embodiment, since the silicon-based compound is used as the transparent resin, it is possible to obtain both the thermal stress buffering effect and the optical element sealing effect described above.

In the optical coupler of one embodiment,
At least a portion excluding the lens member and the transparent resin is sealed with a resin containing a filler.

  According to this embodiment, since the linear expansion coefficient is sealed by the resin containing filler close to the lead frame, the optical element, the bonding wire, etc., the influence of thermal stress on the lead frame, the optical element, etc. Reduced. Therefore, it can be used in a wider temperature range.

In the optical coupler of one embodiment,
The resin containing filler is provided with a resin reservoir for preventing the transparent resin filled between the lens member and the optical surface of the optical element from spreading beyond the area of the lens member.

  According to this embodiment, the liquid transparent resin before curing filled between the lens member and the optical surface of the optical element is prevented from flowing out beyond the region of the lens member. can do. Therefore, it becomes easy to manufacture, and the lens member can be bonded to the lead frame in a state where it is separated from the lead frame by the transparent resin accumulated in the resin reservoir. Furthermore, the number of parts can be reduced by forming the resin reservoir portion with the filler-containing resin.

In the optical coupler of one embodiment,
The resin reservoir has a planar shape that is substantially the same as the planar shape of the lens member, and is a recess that houses the lens member.
A distal end portion of an optical fiber that propagates light entering and exiting the optical element is fitted around the opening in the resin reservoir, and the distal end portion of the fitted optical fiber and the lens are fitted. A connector portion for aligning with the member is provided.

  According to this embodiment, since the resin reservoir and the connector are integrally formed of the filler-containing resin, the size can be reduced. Further, the connector portion to which the tip end portion of the optical fiber is fitted is provided around the opening portion in the resin reservoir portion which is a concave portion for accommodating the lens member. Therefore, only by attaching the tip of the optical fiber to the connector, the lens member and the tip of the optical fiber can be easily aligned with high accuracy.

In the optical coupler of one embodiment,
The lead frame has a through hole,
The optical element is arranged so that the optical surface is positioned in the through hole formed in the lead frame and closes one opening in the through hole,
The lens member is disposed so that the optical axis of the lens passes through the through hole formed in the lead frame and closes the other opening in the through hole.
The transparent resin is filled in the through hole.

  According to this embodiment, the lead frame can be used as a lens barrel of the lens, so that the optical coupler can be reduced in size and the number of parts can be reduced to reduce the cost. Furthermore, since the transparent resin is filled in the through hole of the lead frame, the optical surface of the optical element located immediately below the through hole can be protected.

In the optical coupler of one embodiment,
A protrusion that is inserted into the through hole of the lead frame when the lens member is arranged on the surface facing the lead frame of the lens member so as to close the other opening of the through hole of the lead frame. Is provided.

  According to this embodiment, when the lens member is disposed so as to close the other opening in the through hole of the lead frame, the projection of the lens member is inserted into the through hole. The liquid transparent resin before being filled in the through hole is pushed out of the through hole together with bubbles. Therefore, it is possible to prevent air bubbles from being mixed into the transparent resin after curing in the through hole, and to reduce manufacturing variations in optical characteristics.

In the optical coupler of one embodiment,
The projection of the lens member has a tapered shape in which the dimension in the direction orthogonal to the optical axis decreases as it approaches the tip.

  According to this embodiment, since the protruding portion of the lens member is formed in a tapered shape, the liquid transparent resin in the through hole of the lead frame is continuously extruded by the tapered protruding portion. Leaked. Therefore, it is possible to more reliably prevent bubbles from entering the transparent resin after curing in the through hole, and to reduce the manufacturing variation in optical characteristics.

In the optical coupler of one embodiment,
A groove portion communicating with the through hole of the lead frame and the outside is provided on the surface of the lens member facing the lead frame.

  According to this embodiment, since the lens member is formed with a groove portion that communicates with the through hole of the lead frame and the outside, the lens member opens the other opening in the through hole of the lead frame. When arranged so as to close, the transparent resin in a liquid state before the curing filled in the through hole flows out to the outside together with bubbles through the groove. Therefore, it is possible to prevent bubbles from being mixed into the transparent resin after curing in the through hole, and to reduce manufacturing variations in optical characteristics.

In the optical coupler of one embodiment,
An inner peripheral surface of the through hole of the lead frame is a reflection surface that reflects light incident on or emitted from the optical element.

  According to this embodiment, by making the inner peripheral surface of the through hole of the lead frame a reflective surface, the through hole of the lead frame can be used as an optical path changing member, and the optical coupling efficiency can be achieved with a simple configuration. It is possible to add an optical function such as an improvement.

  As apparent from the above, in the optical coupler of the present invention, the lens member is disposed so that the lens faces the optical surface of the optical element, and the transparent member is disposed between the lens member and the optical surface of the optical element. Since the resin is interposed, it is possible to use a lens that is smaller than a lens formed by a transfer mold for sealing the element, and it is possible to reduce thermal stress applied to the lens member. Accordingly, deformation or breakage of the lens member and peeling from the lead frame can be made difficult to occur.

  Furthermore, the transparent resin can be used as a buffer member for thermal stress generated between the lead frame and the lens member due to a difference in linear expansion coefficient between the lead frame and the lens member. Therefore, it becomes possible to use in a wide temperature range. Moreover, since the transparent resin is interposed between the lens member and the optical surface of the optical element, the optical surface can be protected.

  In the optical coupler of one embodiment, a through hole is formed in the lead frame, the lens member passes through the through hole formed in the lead frame, and the opening of the through hole is formed. Since the through hole is filled with a transparent resin, the lead frame can be used as a lens barrel, and the optical coupler can be reduced in size and the number of parts can be reduced. Can be reduced. Further, since the through hole of the lead frame is filled with the transparent resin, the optical surface of the optical element located immediately below the through hole can be protected.

  Further, in the optical coupler according to one embodiment, since the lens member is provided with a protrusion that is inserted into the through hole of the lead frame, the protrusion of the lens member is inserted into the through hole. The transparent resin that is liquid before being filled in the through hole can be pushed out of the through hole together with bubbles. Therefore, it is possible to prevent air bubbles from being mixed into the transparent resin after curing in the through hole, and to reduce manufacturing variations in optical characteristics.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

First Embodiment FIG. 1 is a longitudinal sectional view of an optical coupler according to the present embodiment. The optical coupler 30 is a device for connecting (so-called optically coupling) the optical element 32 in a state capable of transmitting light with the optical fiber 33 in order to perform optical communication. The optical element 32 is a semiconductor having an optical function, and is, for example, a light emitting element such as a light emitting diode or a surface emitting laser (VCSEL), and a light receiving element such as a photodiode.

  The optical fiber 33 is a cable having flexibility and is formed in an elongated shape, and serves as a light transmission medium that transmits light from one end to the other end. That is, light incident from one end of the optical fiber 33 passes through the optical fiber 33 and exits from the other end of the optical fiber 33. An outer peripheral portion of the one end portion of the optical fiber 33 is covered with a plug 34 that is a coupling portion for coupling to the optical coupler 30.

  The optical coupler 30 is provided with a connector portion 35 into which the plug 34 of the optical fiber 33 is detachably fitted. In a state where the plug 34 is fitted to the connector portion 35, the one end surface 33 a of the optical fiber 33 is arranged at a position facing the optical element 32. That is, when the plug 34 is connected to the connector portion 35, the optical fiber 33 is automatically aligned with the optical element 32.

  As shown in FIG. 1, the optical coupler 30 includes an optical element 32, a lead frame 36, a sealing body 37, a lens member 55, a drive circuit 39, a bonding wire 40, and a transparent adhesive resin 41. It is comprised including. Furthermore, the lead frame 36 is made of a plate-like member having a conductivity of about 100 μm to 500 μm and includes an optical element mounting portion 42, an internal connection portion 43, and an external connection portion 44.

  The optical element 32 is disposed on the surface of the lead frame 36 on the optical fiber 33 side (hereinafter referred to as “surface”) so that the optical surface 46 is located at the center of the optical fiber 33. Hereinafter, the surface of the lead frame 36 on which the optical fiber 33 is not disposed is referred to as a “back surface”. The optical element mounting portion 42 is electrically connected to the drive circuit 39 of the internal connection portion 43 by a bonding wire 40b. The optical element 32 is electrically connected to the external connection portion 44 by a bonding wire 40a. Actually, the connection is made by many other bonding wires, but they are omitted in FIG. Note that the bonding wire 40a represents the bonding wire in the portion filled with the transparent adhesive resin 41, and the bonding wire 40b represents the bonding wire in the portion sealed by the sealing body 37 as a representative.

  A lens member 55 is disposed on the surface side of the optical element mounting portion 42 of the lead frame 36 so as to face the optical element 32. The lens member 55 includes a lens portion 56 that collects light that enters and exits the optical surface 46 of the optical element 32, and an adhesive portion 57 that faces the surface of the lead frame 36. A transparent adhesive resin 41 is filled between the lens member 55 and the lead frame 36. Thus, the transparent adhesive resin 41 is in contact with the surface of the lead frame 36 and the optical surface 46 of the optical element 32, and is also in contact with the adhesive portion 57 of the lens member 55. That is, the optical surface 46 of the optical element 32 and the lens member 55 are bonded via the transparent adhesive resin 41.

  The periphery of the lead frame 36 is sealed (transfer molded) by a sealing body 37 except for the periphery of the optical element 32 on the surface thereof. Thus, the sealing body 37 seals and protects the drive circuit 39 and the bonding wires 40b. In the present embodiment, the above-described connector portion 35 is formed by the sealing body 37.

  Further, a resin reservoir 58 is formed below the connector portion 35 in the sealing body 37. The resin reservoir 58 has a planar shape that is substantially the same as the planar shape of the lens member 55, and includes a hole portion in which the lens member 55 is accommodated. Furthermore, the adhesive resin filling portion 59 formed of a concave portion having a planar shape obtained by reducing the planar shape of the lens member 55 is formed below the resin reservoir portion 58 via a stepped portion. The resin reservoir 58 prevents the liquid transparent adhesive resin 41 filled in the adhesive resin filling portion 59 by a dispenser or the like from overflowing from the adhesive resin filling portion 59 and flowing out beyond the area of the lens member 55. Have a role to play. In addition to filling the transparent adhesive resin 41, the adhesive resin filling portion 59 separates the lens member 55 from the surface of the lead frame 36 by the stepped portion so that the lens member 55 interferes with the optical element 32 and the bonding wire 40 a. It has a role to be able to arrange without being.

  The resin reservoir 58 can be used for alignment between the lens member 55 and the optical element mounting portion 42. That is, the resin reservoir 58 has a planar shape substantially the same as the planar shape of the lens member 55, and the inner diameter of the resin reservoir 58 and the outer diameter of the adhesive portion 57 in the lens member 55 are made substantially equal. Alignment can be performed. Further, in this configuration, the periphery of the opening in the resin reservoir 58 is a step portion into which the plug 34 of the optical fiber 33 is fitted, and the one end surface 33a of the fitted optical fiber 33 and the lens. Since the connector portion 35 that aligns with the portion 56 is formed, the alignment of the optical fiber 33 and the alignment of the lens member 55 can be performed by the same member, and high-precision and simple assembly is achieved. It can be done.

  The optical coupler 30 is electrically connected to a control device (not shown) which is an external device, and transmits and receives electrical signals to and from the control device. When the optical element 32 is a light emitting element, the control device supplies a light emission command as the electric signal to the drive circuit 39. Then, the drive circuit 39 causes the optical surface 46 of the light emitting element (optical element) 32 to emit light in accordance with the supplied light emission command (electrical signal). The light emitted from the optical surface 46 enters the lens member 55, is collected by the lens unit 56, and enters the one end surface 33 a of the optical fiber 33.

  On the other hand, when the optical element 32 is a light receiving element, the light emitted from the one end surface 33a of the optical fiber 33 is incident on the lens member 55 and is condensed by the lens unit 56 to be received by the light receiving element (optical element). ) 32 is incident on the optical surface 46. The light receiving element 32 generates an electrical signal (for example, a voltage signal) corresponding to the light (for example, the amount of light) incident on the optical surface 46, and outputs the generated electrical signal to the drive circuit 39 or the control device. is there.

  In this way, the optical coupler 30 couples the optical element 32 and the optical fiber 33 so as to be able to transmit light, converts the electric signal supplied from the control device into an optical signal, and radiates from the optical element 32. can do. Alternatively, an optical signal incident on the optical element 32 can be converted into an electrical signal and output to the control device.

  Next, in the present embodiment, the reason why the influence of the thermal stress due to the change of the environmental temperature can be reduced is compared with the first prior art (see FIG. 9) and the second prior art (see FIG. 10). explain. The difference between the optical coupler 30 in the present embodiment and the optical couplers 1 and 11 in the first and second prior arts is mainly in the following three points. (A) Since the lens member 55 is not formed integrally with the sealing body 37 by transfer molding, a small lens member 55 can be used. (B) The lens member 55 is bonded to the lead frame 36 via the transparent adhesive resin 41. (C) The surface of the optical surface 46 of the optical element 32 is sealed with a transparent adhesive resin 41. Due to this difference, the following effects can be achieved.

  That is, in the conventional optical coupler 1 (see FIG. 9), the lens portion 6 is formed of the transparent mold resin 4, and the transparent mold resin 4 is a sealing body including the lead frame 2. In such a configuration, the difference in linear expansion coefficient between the lead frame 2 and the transparent mold resin 4 is large, and the thermal stress at the interface between the two is high. Accordingly, the transparent mold resin 4 is damaged (cracked), the transparent mold resin 4 is peeled off from the lead frame 2, or the lens portion 6 is deformed.

  On the other hand, in the present optical coupler 30, the lens member 55 (the portion corresponding to the transparent mold resin 4 and the lens portion 6 of the optical coupler 1) does not necessarily need to be formed by transfer molding. Even if it is formed by, it becomes easy to reduce the size. As a result, the contact area between the sealing body 37 and the lead frame 36 can be reduced, and the lens member 55 is bonded to the lead frame 36 via the transparent adhesive resin 41. The lead frame 36 and the lens member 55 can be used as a buffer member for thermal stress due to a difference in linear expansion coefficient. Therefore, the thermal stress acting on the lens member 55 can be significantly reduced, and damage or deformation of the lens member 55 can be prevented. In particular, it is more preferable to use a resin having a low Young's modulus such as a silicon-based resin as the transparent adhesive resin 41 because the buffering effect of the transparent adhesive resin 41 becomes higher. Furthermore, the stress acting on the optical element 32 and the bonding wire 40a can be reduced by the transparent adhesive resin 41.

  Further, as a secondary effect, in the present embodiment, unlike the first and second conventional examples, the sealing body 37 (the transparent mold resins 4 and 16 of the optical couplers 1 and 11 are added). For example, milky white resin to which a filler such as silica is added, or black resin used for IC (integrated circuit) sealing can be used. Therefore, these milky white and black resins can have the same linear expansion coefficient as that of the lead frame 36 by the addition of the filler, so that the influence of thermal stress can be reduced. That is, the thermal stress applied to the entire optical coupler 30 can be reduced, and the stress acting on the sealing body 37, the bonding wire 40b, and the drive circuit 39 can be reduced.

  On the other hand, in the conventional optical coupler 11 (see FIG. 10), the transparent mold resin 16 filled in the through hole 15 is peeled off from the surface of the optical element 12 due to thermal stress, and the optical element 12 There is a problem that characteristics change. This is also because the contact area between the transparent mold resin 16 and the lead frame 13 is large, and the thermal stress between the transparent mold resin 16 and the optical surface 17 is increased in the through hole 15.

  In the present optical coupler 30, the use of a resin having a low Young's modulus as described above as the transparent adhesive resin 41 has a stress relieving effect, and the transparent adhesive resin 41 selects an arbitrary material depending on the bonding partner. And a resin having a stronger adhesive force to the lead frame 36 and the optical surface 46 than the transparent mold resin 16 generally used in transfer molding can be selected. Therefore, the transparent adhesive resin 41 and the lens from the optical surface 46 can be selected. The peeling of the member 55 can be prevented, and the highly reliable optical coupler 30 can be obtained.

  Hereinafter, the material of each part will be described in detail.

  First, the lens member 55 is made of a resin such as polymethyl methacrylate (PMMA), polycarbonate, cycloolefin, or a low-melting glass, and processed into an arbitrary shape by injection molding or the like. Can be used.

  As the transparent adhesive resin 41, it is preferable to use a material excellent in light transmittance and to use a material having a refractive index close to that of the lens member 55 in order to reduce reflection loss. Further, as described above, it is preferable to use a material having a Young's modulus of 1 GPa or less in order to relieve thermal stress. Specifically, for example, an epoxy resin, a silicon resin, or the like can be used. In particular, a silicon-based resin is more preferable because it has a low Young's modulus, a high thermal stress relaxation effect as described above, and a high sealing effect for the optical element 32.

  The sealing body 37 is generally made of a material obtained by adding a filler to an epoxy resin used for sealing a semiconductor element, and has a linear expansion coefficient close to that of the bonding wire (Au or Al) 40b. A material with high thermal conductivity is used. For example, when the bonding wire 40b is Au having a linear expansion coefficient of 14.2 ppm / K, the linear expansion coefficient of the sealing body 37 is preferably set to 20 ppm / K or less (usually filler is added). The linear expansion coefficient of non-epoxy resins is about 60 ppm / K). The thermal conductivity of the sealing body 37 is preferably set to 0.6 W / m · K or more (usually, the thermal conductivity of an epoxy-based resin not added with a filler is 0.2 W / m · K. degree).

  As the optical element 32, in addition to the LED and the PD, a CCD (Charge Coupled Device), the VCSEL, and the optical element 32 and an integrated circuit (IC) are integrated. An opto-electronic integrated circuit (OEIC) or the like can be used. The optical wavelength of the optical element 32 is preferably a wavelength with little transmission loss due to the optical fiber 33 coupled to the optical coupler 30.

  The optical fiber 33 is preferably a multimode optical fiber such as a plastic optical fiber (POF) or a quartz glass optical fiber (GOF). In the POF, the core is made of a plastic having excellent light transmittance such as PMMA and polycarbonate, and the clad is made of a plastic having a refractive index lower than that of the core. The POF can easily have a core diameter of 200 μm or more as compared with the GOF. Therefore, by using the POF, the coupling with the optical coupler 30 can be easily adjusted and can be manufactured at a low cost.

  The optical fiber 33 may be a PCF (Polymer Clad Fiber) having a core made of quartz glass and a clad made of polymer. This PCF has a feature that it is higher in price than the POF but has a small transmission loss and a wide transmission band. Therefore, by using the PCF as a transmission medium, an optical communication network capable of long-distance communication and higher-speed communication can be configured.

  The lead frame 36 has a thickness of about 100 μm to 500 μm. As the lead frame 36, a thin metal plate made of a metal having conductivity and high thermal conductivity is used. For example, copper, its alloy, and 42 alloy containing about 42% nickel in iron. An iron alloy such as is used. The surface of the lead frame 36 may be plated with silver, gold, palladium, or the like in order to improve the corrosion resistance.

  The optical coupler 30 having the above configuration is manufactured as follows. First, the drive circuit 39 is bonded and electrically connected to the lead frame 36, and the sealing body 37 is formed by performing transfer molding. At this time, the surface side of the lead frame 36 is pressed by a mold, and the sealing body 37 is formed on the portion of the lead frame 36 where the optical element mounting portion 42 and the external connection portion 44 are formed with the adhesive resin filling portion 59 on the surface side. Prevents the resin from wrapping around. Thereafter, the optical element 32 is bonded to the optical element mounting portion 42 and electrically connected by the bonding wire 40a, and the transparent adhesive resin 41 is filled into the adhesive resin filling portion 59 by a dispenser or the like. Next, the lens member 55 is inserted into the resin reservoir 58 and bonded to the optical element mounting portion 42 of the lead frame 36. At that time, the lens member 55 and the optical element mounting portion 42 are aligned by the resin reservoir 58 having a planar shape substantially the same as the planar shape of the lens member 55. Further, in this configuration, the periphery of the opening in the resin reservoir 58 is a step portion into which the plug 34 of the optical fiber 33 is fitted, and the one end surface 33a of the fitted optical fiber 33 and the lens. Since the connector portion 35 that aligns with the portion 56 is formed, the alignment of the optical fiber 33 and the alignment of the lens member 55 can be performed by the same member, and high-precision and simple assembly is achieved. It can be done. Then, the optical coupler 30 is completed by curing the transparent adhesive resin 41. The transparent adhesive resin 41 is cured by heating, ultraviolet irradiation or the like, although it varies depending on the adhesive used.

Second Embodiment The optical coupler 31 in the present embodiment is provided with a through hole in a lead frame, and an optical element is disposed at the position of the through hole on the back surface of the lead frame.

  FIG. 2 is a longitudinal sectional view of the optical coupler 31 of the present embodiment. However, members having the same configuration as the configuration of the optical coupler 30 shown in FIG.

  In FIG. 2, a through hole 45 is formed in the optical element mounting portion 42 of the lead frame 36, and the optical element 32 is positioned on the back surface of the lead frame 36 and the optical surface 46 is positioned in the center of the through hole 45. Is arranged. The optical element 32 is electrically connected to the external connection portion 44 by a bonding wire 40.

  A lens member 38 is disposed on the surface side of the optical element mounting portion 42 of the lead frame 36 so as to face the through hole 45. The lens member 38 has a lens portion 47 that collects light that enters and exits the optical surface 46 of the optical element 32, a protrusion 48 that is inserted into the through hole 45, and an adhesive that faces the surface of the lead frame 36. Part 49. A transparent adhesive resin 41 is filled between the protrusion 48 of the lens member 38 and the optical surface 46 of the optical element 32 in the through hole 45. Thus, the transparent adhesive resin 41 is in contact with the surface of the lead frame 36 and the optical surface 46, and is also in contact with the adhesive portion 49 and the protrusion 48 of the lens member 38. That is, the optical surface 46 of the optical element 32 and the lens member 38 are bonded via the transparent adhesive resin 41.

  The through hole 45 of the lead frame 36 also serves as a lens barrel for fixing the lens member 38. Thus, by using the through hole 45 of the lead frame 36 as a lens barrel for fixing the lens member 38, the number of parts can be reduced and the size can be reduced. Further, since the optical element 32 and the lens member 38 can be arranged without using the bonding wire 40, the distance between them can be arranged close to each other. Therefore, even when a light emitting element having a relatively wide radiation angle, such as an LED, is used as the optical element 32, high light utilization efficiency can be realized.

  The optical element 32 is sealed (transfer molded) by a sealing body 37 except for the optical surface 46. Thus, the sealing body 37 seals and protects the optical element 32, the drive circuit 39, the bonding wire 40, and the like. In the present embodiment, the above-described connector portion 35 is formed by the sealing body 37.

  When the optical element 32 is a light emitting element, light emitted from the optical surface 46 of the light emitting element (optical element) 32 passes through the through hole 45 and enters the lens member 38. On the other hand, when the optical element 32 is a light receiving element, the light emitted from the one end surface 33a of the optical fiber 33 enters the lens member 38, is condensed by the lens portion 47, passes through the through hole 45, and The light is incident on the optical surface 46 of the light receiving element (optical element) 32.

  Also in the case of the present embodiment, since the lens member 38 is bonded to the lead frame 36 via the transparent adhesive resin 41, the difference in linear expansion coefficient between the lead frame 36 and the lens member 38 is used as the transparent adhesive resin 41. It can be used as a thermal stress buffer member.

  Even if the transparent adhesive resin 41 is not filled in the through hole 45 but is filled only between the adhesion portion 49 of the lens member 38 and the surface side of the lead frame 36, a thermal stress relaxation effect can be expected. However, when the transparent adhesive resin 41 leaks into a part of the optical path, the optical characteristics of the present optical coupler 31 change, which makes it difficult to manufacture the optical coupler 31. In particular, when the lens member 38 is downsized, the manufacture becomes difficult. In addition, it is difficult to obtain an effect of improving optical characteristics by covering the optical surface 46 (an improvement in external extraction efficiency and a reduction in reflectance) and a sealing effect of the optical element 32 from the outside air. In contrast, when the transparent adhesive resin 41 is filled in the through hole 45 as in the present embodiment, moisture and impurities can be prevented from adhering to the optical surface 46, and the moisture resistance of the optical coupler 31 can be prevented. Can be improved. Therefore, from the viewpoint of protecting the optical element 32 and stabilizing the optical characteristics, it is preferable to fill the through hole 45 with the transparent adhesive resin 41.

  Further, when compared with the optical coupler 21 (see FIG. 11) in the third prior art, the present optical coupler 31 can use the thin plate-like lead frame 36 as a lens barrel, so that the cost is low. Yes, it is easy to reduce the number of parts and downsize. Furthermore, the formation of the through hole 45 of the lead frame 36 can be performed simultaneously with the formation of other patterns of the lead frame 36 by pressing or etching, and there is an advantage that the cost can be reduced.

  Next, a manufacturing method of the present optical coupler 31 will be described with reference to FIG. First, as shown in FIG. 3A, the optical element 32 and the drive circuit 39 are aligned and bonded to the lead frame 36, and the back electrode (not shown) of the optical element 32 and the drive circuit are bonded by wire bonding. 39 and the lead frame 36 are electrically connected by a bonding wire 40.

  In that case, a conductive material such as Ag paste, solder, or gold eutectic bonding is used for bonding, and the electrode formed on the optical surface 46 side of the optical element 32 and the lead frame 36 are electrically connected. Glue so that. Alternatively, when an electrical connection is not required, a transparent adhesive having no conductivity may be used. When this transparent adhesive is used, it is possible to prevent the adhesive from adhering to the optical surface 46 to deteriorate the optical characteristics, and particularly when a small optical element 32 such as an LED or PD is used. preferable. Here, even if the adhesive is usually a transparent adhesive, when the adhesive adheres to the optical surface 46, the optical characteristics change because the refractive index of the surface of the optical surface 46 changes. However, in this embodiment, in order to later seal the inside of the through hole 45 with the transparent adhesive resin 41, the refractive index of the transparent adhesive resin 41 and the refractive index of the adhesive for bonding the optical element 32 are made equal. If set, there is an advantage that the optical characteristics do not change.

  Next, as shown in FIG. 3B, the sealing body 37 is formed by performing transfer molding. At this time, the surface side of the lead frame 36 is pressed by a mold to prevent the resin of the sealing body 37 from entering the portion of the optical element mounting portion 42 of the lead frame 36 where the surface side lens member 38 is bonded. .

  Next, as shown in FIG. 3C, the transparent adhesive resin 41 is filled into the through hole 45 of the optical element mounting portion 42 by a dispenser or the like. It is preferable that a resin reservoir 50 is formed below the connector portion 35 in the sealing body 37. The resin reservoir 50 has a planar shape that is substantially the same as the planar shape of the lens member 38, and is constituted by a recess in which the lens member 38 is accommodated. The resin reservoir 50 prevents the liquid transparent adhesive resin 41 filled in the through hole 45 of the lead frame 36 from overflowing from the through hole 45 and flowing out to the outside beyond the area of the lens member 38. The member 38 is floated from the surface of the lead frame 36 by the transparent adhesive resin 41 and has a role of preventing the lens member 38 from contacting the lead frame 36. The amount of the transparent adhesive resin 41 may be reduced so that it does not overflow from the through hole 45. However, if the transparent adhesive resin 41 is small, the lens member 38 is caused by capillary action when the lens member 38 is installed. There is a problem that the transparent adhesive resin 41 comes out of the gap between the lead frame 36 and the through hole 45 cannot be completely filled with the transparent adhesive resin 41 (air bubbles enter).

  Next, as shown in FIG. 3 (d), the protruding portion 48 of the lens member 38 is inserted into the through hole 45, and the lens member 38 is bonded to the optical element mounting portion 42 of the lead frame 36. The resin reservoir 50 can be used for positioning the lens member 38 and the optical element mounting portion 42. That is, the alignment is performed by having a planar shape substantially the same as the planar shape of the lens member 38 and by making the inner diameter of the resin reservoir 50 and the outer diameter of the bonding portion 49 of the lens member 38 substantially equal. It can be done.

  By inserting the protruding portion 48 of the lens member 38 into the through hole 45, a part of the transparent adhesive resin 41 filled in the through hole 45 is pushed out by the protruding portion 48 of the lens member 38 from the through hole 45. It overflows to the surface side of the optical element mounting portion 42 and is accumulated in the resin reservoir 50 of the sealing body 37. As a result, in a state where the lens member 38 is disposed at the position of the optical element mounting portion 42, as shown in FIG. 3D, the lens member 38 (adhesive portion 49) is interposed between the surface of the optical element mounting portion 42. The transparent adhesive resin 41 is filled. Further, the transparent adhesive resin 41 is also filled around the protrusion 48. Then, the optical coupler 31 is completed by curing the transparent adhesive resin 41. The transparent adhesive resin 41 is cured by heating, ultraviolet irradiation, or the like, although it varies depending on the adhesive used.

  As shown in FIG. 2, the projection 48 of the lens member 38 is a so-called taper in which the dimension in the direction perpendicular to the optical axis of the lens part 47 (the dimension in the left-right direction in FIG. 2) decreases as it approaches the tip. It has a shape. By doing so, the transparent adhesive resin 41 continuously overflows from the through hole 45, and the lens member 38 can be uniformly bonded with the transparent adhesive resin 41. In addition, there is an effect of preventing bubbles from entering the through hole 45. That is, even when bubbles are involved in the through hole 45 when the lens member 38 is installed, the bubbles can be discharged together with the overflowing transparent adhesive resin 41. The taper shape of the protrusion 48 is optimized to an arbitrary shape and size according to the amount of the transparent adhesive resin 41 to overflow.

  Further, the protrusion 48 has a function of reducing the amount (volume) of the transparent adhesive resin 41 filled in the through hole 45. By reducing the volume of the transparent adhesive resin 41, the amount of volume fluctuation due to thermal shrinkage is reduced, so that it can be made less susceptible to thermal stress. Furthermore, since the bonding area between the lens member 38 and the transparent adhesive resin 41 is increased by the formation of the protrusion 48, there is an effect that the adhesion force of the lens member 38 to the lead frame 36 is improved.

  As described above, when the through hole 45 is filled with the transparent adhesive resin 41 as in the present optical coupler 31, bubbles are mixed into the transparent adhesive resin 41 at the time of manufacturing (when the lens member 38 is bonded). Therefore, it is important to devise the shape of the lens member 38. Here, a desirable shape of the lens member 38 will be described with reference to FIG.

  FIG. 4 shows an example of the shape of the lens member 38. 4A is a plan view of the lens member 38 viewed from the lens portion 47 side, FIG. 4B is a longitudinal sectional view, and FIG. 4C is a bottom view viewed from the optical element 32 side. is there. The bonding portion 49 has a flat surface facing the lead frame 36 and is a stopper (a distance from the surface of the optical element mounting portion 42 is kept constant) when the protrusion 48 is inserted into the through hole 45. Has a function. The lens member 38 is preferably formed by injection molding, which is an inexpensive method, and the adhesive portion 49 also functions as a gate portion and an ejector pin pressing portion during injection molding. Furthermore, it is preferable to form a resin outflow part (groove part) 51 extending in the radial direction from the protrusion part 48 on the surface of the adhesive part 49 facing the lead frame 36. The resin outflow portion 51 has a role of discharging the transparent adhesive resin 41 that flows out when the protrusion 48 is inserted into the through hole 45 toward the resin reservoir 50, and forms the resin outflow portion 51. As a result, the transparent adhesive resin 41 can be formed more uniformly, and air bubbles can be prevented more reliably. In addition, since the resin outflow portion 51 is formed continuously with the protrusion 48, the transparent adhesive resin 41 including the bubbles pushed out from the through hole 45 by the protrusion 48 can be efficiently discharged. preferable.

  Further, it is preferable to form a bowl-shaped resin pressing portion 52 on the outer peripheral edge of the adhesive portion 49 in the lens member 38. The resin pressing portion 52 has a function of preventing the liquid transparent adhesive resin 41 from wrapping around the surface side (lens portion 47 side) of the lens member 38, and the transparent adhesive resin 41 adheres to the lens portion 47 and has characteristics. It prevents changes.

  The viscosity of the transparent adhesive resin 41 is preferably set to 10 Pa · s or less so that bubbles are not mixed when injected into the through hole 45. Further, the sealing body 37 is made of a material having a high coefficient of linear thermal expansion and a thermal expansion coefficient close to those of the optical element (Si or GaAs) 32 and the bonding wire (Au or Al) 40. For example, when the optical element 32 and the bonding wire 40 have an Si linear expansion coefficient of 2.8 ppm / K and an Au linear expansion coefficient of 14.2 ppm / K, the linear expansion of the sealing body 37 is performed. The coefficient is preferably set to 20 ppm / K or less (usually, the linear expansion coefficient of an epoxy resin to which no filler is added is about 60 ppm / K).

  Next, the results of a temperature cycle test using the present optical coupler 31 will be described. For comparison, a comparative test was also conducted using the optical couplers 1 and 11 of the first and second prior arts (see FIGS. 9 and 10).

The following four types of samples were prepared. The temperature cycle conditions were a low temperature side of −40 ° C. and a high temperature side of 115 ° C., and the standing time at each temperature was 15 minutes. The number of cycles was 3000, and the state was confirmed every 100 cycles.
Sample A: This optical coupler 31 shown in FIG. 2: a silicon-based resin is used as the transparent adhesive resin 41 Sample B: This optical coupler 31: an epoxy-based resin is used as the transparent adhesive resin 41 Sample C : First optical coupler 1 shown in FIG.
Sample D: Second prior art optical coupler 11 shown in FIG.

  The common members are LEDs having a wavelength of 650 nm (light emitting part diameter φ150 μm) as the light emitting elements 32, 3 and 12, and copper alloys having a thickness of 250 μm as the lead frames 36, 2 and 13 (linear expansion coefficient of 17. ppm / K) And gold having a wire diameter of 25 μm was used as the bonding wires 40, 8 and 18. In addition, as a member unique to each sample, the lens member 38 is made of polycarbonate, the sealing body 37 is made of an epoxy resin containing filler (linear expansion coefficient 18 ppm / K), and the transparent mold resins 4 and 16 are free of filler. Epoxy resin (linear expansion coefficient 65 ppm / K) was used. Further, as the transparent adhesive resin 41, a silicon-based resin (Young's modulus of 1 MPa) was used in Sample A, and an epoxy-based resin (Young's modulus of 3 GPa) was used in Sample B.

  When a temperature cycle test was performed under the above conditions, in Sample C and Sample D, defects occurred within 300 cycles. That is, in the sample C, the transparent mold resin 4 was cracked and the bonding wire 8 was broken. In Sample D, in addition to the same defects, a sample in which the amount of light incident on the optical fiber 14 (transmitted light amount) was reduced by about 50% was also observed. This is considered to be because the transparent mold resin 16 peeled off from the optical surface 17 due to thermal stress, and the light extraction efficiency of the LED (optical element) 12 was halved.

  On the other hand, in Sample A, even after the end of 3000 cycles, the amount of transmitted light was within ± 10%, and the lens member 38 was neither deformed nor damaged. In Sample B, there was a sample in which the amount of transmitted light was reduced by about 20%, but no other problems occurred. In this sample B, an epoxy resin having a high Young's modulus was used as the transparent adhesive resin 41. Therefore, it is considered that the transparent adhesive resin 41 was partially peeled from the optical surface 46 due to thermal stress.

  Thus, in the optical couplers 1 and 11 according to the first and second prior arts, cracks in the transparent mold resins 4 and 16 and half of the amount of transmitted light occurred in the temperature cycle test due to the influence of thermal stress. On the other hand, in the optical coupler 31 of this Embodiment, the above defects did not occur. In particular, it has been proved that the effect appears remarkably when a silicon-based resin having a low Young's modulus is used as the transparent adhesive resin 41.

Here, the shear stress (in the case of −40 ° C.) acting on the adhesive surface between the optical element 32 (the surface is SiO ₂ ) and the transparent adhesive resin 41 was obtained by simulation using a finite element method. The epoxy resin (Young's modulus 3 GPa, linear expansion coefficient 70 ppm / K) was 66 MPa. On the other hand, when the adhesive strength (shear adhesive strength) between the optical element 32 and the transparent adhesive resin 41 was measured, the epoxy resin used in the sample B was 40 MPa, and the shear stress due to heat was higher than the adhesive strength. It is getting bigger. On the other hand, when calculation was performed with an epoxy resin having a lower Young's modulus (Young's modulus 1 GPa, linear expansion coefficient 70 ppm / K), the shear strength was 22 MPa and the adhesive strength was higher. Using the latter resin, the above-described temperature cycle test was performed. As a result, the variation in the amount of transmitted light was within ± 10%, which was the same as that of the silicon-based resin. From the above, as the transparent adhesive resin 41, it is preferable to use a resin having a high stress relaxation effect and a Young's modulus of 1 GPa or less. In particular, a silicon-based resin is more preferable because it has a low Young's modulus and has a sealing effect on the optical element 32.

  Of course, also in the optical couplers 1 and 11 in the first and second prior arts, if the temperature range is narrowed (for example, about −20 ° C. to 80 ° C.), the above-described problem does not occur. That is, by using the optical coupler 31 in the present embodiment, it can be used in a wider temperature range.

  Hereinafter, modifications of the optical coupler according to this embodiment will be described with reference to FIGS. However, members having the same configuration as the configuration of the optical coupler 31 shown in FIG. 5 to 8 are schematic views for explaining the main points of the configuration different from the configuration of the optical coupler 31 shown in FIG. 2, and the optical elements 32, the lens member 38, and the lead frame 36 are mounted with the optical elements. Members other than the part 42, the transparent adhesive resin 41, the sealing body 37, and the members corresponding thereto are omitted.

  The optical coupler 61 shown in FIG. 5 has a tapered shape in which the through-hole 62 in the optical element mounting portion 42 of the lead frame 36 has a small diameter on the side where the optical element 32 is disposed (the diameter is approximately equal to the size of the optical surface 46). It is what. In the above configuration, the inner peripheral surface 63 of the through hole 62 is used as a reflection mirror. Here, when a light emitting element such as an LED is used as the optical element 32, light having a narrow emission angle out of the light emitted from the light emitting element 32 passes through the through-hole 62 as it is and enters the lens unit 47. The light is refracted and enters the optical fiber 33. On the other hand, of the light radiated from the optical element 32, light having a wide radiation angle is reflected by the taper portion (inner peripheral surface 63) of the through hole 62, and then is incident on the lens portion 47 and refracted. 33 is incident. Therefore, even when an LED having a wide radiation angle is used as the optical element 32, the light emitted from the optical element 32 can be incident on the optical fiber 33 with high efficiency.

  Even when a light receiving element such as a PD is used as the optical element 32, a high light collecting effect can be obtained by reflecting incident light by the tapered portion (inner peripheral surface 63) of the through hole 62. The through-hole 62 can be formed simultaneously with the patterning of the lead frame 36 by etching, pressing, or the like, so that a low-cost optical coupler 61 can be obtained without increasing the price.

  The optical coupler 71 shown in FIG. 6 is obtained by interposing a submount 73 between the through hole 72 and the optical element 32 in the optical element mounting portion 42 of the lead frame 36. In the above configuration, the submount 73 is formed with a light passage portion 74 formed by a hole penetrating in the thickness direction or a light passage portion 74 formed by filling the hole with an optically transparent material. . The optical element 32 is bonded to the submount 73. An electrode (not shown) that is electrically connected to an electrode (not shown) of the optical element 32 is formed on the submount 73, and the lead frame 36 and the driver circuit 39 are connected to the submount 73 by a bonding wire (not shown). It can also be electrically coupled. The through hole 72 of the lead frame 36 is formed to have a larger diameter than the large diameter portion of the light passage portion 74 of the submount 73. Further, since the lead frame 36 and the submount 73 do not necessarily have to be electrically coupled, they can be bonded by an arbitrary adhesive.

  As the submount 73, an Si substrate, a glass substrate, or the like can be used. For example, when an Si substrate is used, it is preferable to use a through hole obtained by processing a single crystal Si substrate by anisotropic etching as the light passage portion 74. For example, by etching the (100) plane of the single crystal Si with KOH (potassium hydroxide), the (111) plane having an angle of 54.74 ° can be obtained as a smooth surface having an accurate angle. In this case, as in the case of the optical coupler 61 shown in FIG. 5, compared to the case where the through hole 62 of the lead frame 36 is processed into a tapered shape, the processing accuracy and surface accuracy are better, and the performance as a reflection mirror is higher. Can be obtained. Furthermore, Si has high thermal conductivity, and when Si is used as the optical element 32, there is no difference in linear expansion coefficient between the submount (Si substrate) 73 and the optical element 32, and stress or heat applied to the optical element 32 are not affected. The resistance can be reduced.

  Further, a glass substrate may be used as the submount 73. Since the glass substrate is optically transparent, it is not necessary to form a through hole as the light passage portion 74. Furthermore, Pyrex glass or the like has a linear expansion coefficient close to that of Si (optical element 32), and the stress on the optical element 32 can be reduced by selecting the type of glass. Furthermore, it is possible to form a convex lens or a Fresnel lens in the light passage portion 74 to condense incident / exiting light.

  The optical coupler 81 shown in FIG. 7 uses a lens member 82 in which no projection corresponding to the projection 48 formed on the lens member 38 of the optical coupler 31 shown in FIG. 2 is formed. In the above configuration, for example, when the transparent adhesive resin 41 having a low viscosity (0.1 Pa · s or less) is used, the fluidity of the transparent adhesive resin 41 is high and bubbles are easily discharged. For this reason, the formation of the lens member 82 can be easily achieved by forming the resin outflow portion (groove portion) 51 without forming the protrusions on the lens member 82 and sufficiently suppressing the generation of bubbles. Become.

  In the optical coupler 91 shown in FIG. 8, a resin reservoir 93 is formed not on the sealing body 94 but on the lead frame 92. In the above configuration, the resin reservoir portion 93 is formed by forming a recess having a planar shape substantially the same as the planar shape of the lens member 38 on the surface of the outer peripheral portion of the through hole 95 in the lead frame 92. For example, when the connector part 35 (see FIG. 2) is not formed by the sealing body 94, the optical coupler 91 can be thinned by not forming the sealing body 94 on the surface side of the lead frame 92. Can do. In such a case, the same function as that of the resin reservoir 50 in the optical couplers 31, 61, 71, 81 can be obtained by forming the resin reservoir 93 in the lead frame 92.

  As described above, according to the optical couplers 30, 31, 61, 71, 81, 91 in the present embodiment, the thermal stress generated in the lens members 55, 38, 82 can be reduced, and the filler can be used. Since it can seal with the added sealing bodies 37 and 94, it becomes possible to use it in the environment of a wide temperature range like -40 degreeC to 115 degreeC, for example. Further, the lead frames 36 and 92 can be used as a lens barrel for fixing the lens members 38 and 82, and the number of parts is reduced, and the small and inexpensive optical couplers 31, 61, 71, 81, 91 are used. Can be obtained. Furthermore, by devising the shape of the lens members 38 and 82, it is possible to obtain 31, 61, 71, 81, and 91 which can obtain stable performance without mixing of bubbles.

It is a longitudinal cross-sectional view in 1st Embodiment of the optical coupler of this invention. It is a longitudinal cross-sectional view in 2nd Embodiment. It is a longitudinal cross-sectional view which shows the preparation procedures of the optical coupler shown in FIG. It is explanatory drawing of the shape of the lens member in FIG. It is a figure which shows the modification of the optical coupler shown in FIG. It is a figure which shows the modification different from FIG. It is a figure which shows the modification different from FIG. 5 and FIG. It is a figure which shows the modification different from FIGS. It is a longitudinal cross-sectional view in the conventional optical coupler. It is a longitudinal cross-sectional view in the conventional optical coupler different from FIG. It is a longitudinal cross-sectional view in the conventional optical coupler different from FIG. 9 and FIG.

Explanation of symbols

30, 31, 61, 71, 81, 91 ... optical coupler,
32. Optical element,
33 ... optical fiber,
34 ... plug,
35 ... Connector part,
36,92 ... lead frame,
37, 94 ... sealed body,
38, 55, 82 ... lens member,
39 ... Drive circuit,
40, 40a, 40b ... bonding wire,
41 ... Transparent adhesive resin,
45, 62, 72, 95 ... through holes,
46: Optical surface,
47, 56 ... Lens part,
48 ... protrusions,
49, 57 ... Adhesive part,
50, 58, 93 ... Resin reservoir,
51. Resin outflow part (groove part),
52. Resin holding part,
59 ... Adhesive resin filling part,
63 ... the inner peripheral surface of the through hole,
73 ... Submount,
74: Light passage portion.

Claims (12)

An optical element;
A lead frame mounted with the optical element and electrically connected to the optical element;
A lens member including a lens that collects light incident on or emitted from the optical element;
The lens member is disposed so that the lens faces an optical surface that is a surface on which light in the optical element is incident or emitted,
A transparent coupler is interposed between the lens member and the optical surface of the optical element. The optical coupler according to claim 1.
The transparent resin is also spread on the surface of the lead frame where the lens member is disposed,
An optical coupling characterized in that the lens member is bonded to the lead frame via the transparent resin spreading on the surface of the lead frame, and is not in direct contact with the lead frame. vessel. The optical coupler according to claim 1 or 2,
The transparent resin has a Young's modulus of 1 GPa or less. The optical coupler according to any one of claims 1 to 3,
The optical coupler is characterized in that the transparent resin is a silicon compound. The optical coupler according to any one of claims 1 to 4,
An optical coupler, wherein at least a portion excluding the lens member and the transparent resin is sealed with a resin containing a filler. The optical coupler according to claim 5.
The resin containing filler is provided with a resin reservoir for preventing the transparent resin filled between the lens member and the optical surface of the optical element from spreading beyond the area of the lens member. Optical coupler. The optical coupler according to claim 6.
The resin reservoir has a planar shape that is substantially the same as the planar shape of the lens member, and is a recess that houses the lens member.
A distal end portion of an optical fiber that propagates light entering and exiting the optical element is fitted around the opening in the resin reservoir, and the distal end portion of the fitted optical fiber and the lens An optical coupler comprising a connector portion for aligning with a member. The optical coupler according to any one of claims 1 to 7,
The lead frame has a through hole,
The optical element is arranged so that the optical surface is positioned in the through hole formed in the lead frame and closes one opening in the through hole,
The lens member is disposed so that the optical axis of the lens passes through the through hole formed in the lead frame and closes the other opening in the through hole.
An optical coupler, wherein the through hole is filled with the transparent resin. The optical coupler according to claim 8.
A protrusion that is inserted into the through hole of the lead frame when the lens member is arranged on the surface facing the lead frame of the lens member so as to close the other opening of the through hole of the lead frame. An optical coupler comprising a portion. The optical coupler according to claim 9, wherein
The projection of the lens member has a tapered shape in which a dimension in a direction orthogonal to the optical axis decreases as it goes toward the tip. The optical coupler according to any one of claims 8 to 10,
The optical coupler according to claim 1, wherein a groove portion communicating with the through hole of the lead frame and the outside is provided on a surface of the lens member facing the lead frame. The optical coupler according to any one of claims 8 to 11,
The optical coupler according to claim 1, wherein an inner peripheral surface of the through hole of the lead frame is a reflecting surface that reflects light incident on or emitted from the optical element.

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